Beta diversity and specialization in plant-pollinator networks along an elevational gradient

Aim: To assess whether the reduced nutritional resources available for pollinators due to plant community simplification along an elevational plant-diversity gradient changes pollinator niche breadth and richness. Additionally, we evaluated how body size and proboscis length of pollinators shifted along the gradient, and whether these changes were related to pollinator niche breadth. Location: An elevational gradient (2,350-3,520 m a.s.l.) on the oceanic high-mountain strato-volcano of El Teide (Tenerife, Canary Islands). Taxon: Flowering plant and pollinator species. Methods: We compared quantitative plant–pollinator networks along the plant-diversity gradient. We calculated a set of niche-based topological metrics that capture the degree of specialization, niche breadth and niche overlap. Furthermore, we obtained β-diversity measures and the proportion of replacement and richness components. Results: There was an overall decline in species richness of pollinators with increasing e...